Crossing the Line
by ladyylazarus
Summary: "'Snape, move it' yelled James. Snape could see a monstrous shape sprinting down the tunnel. As it came closer, he saw its yellow eyes and heard its jaws snapping violently. It howled; an eerie, feral moan. He felt his body go rigid with fear. This was far beyond anything he had expected." - The story of how James Potter saved the life of Severus Snape.
1. Part I

_**Crossing the Line: Part I**_

Night was just beginning to fall in earnest, the first stars appearing out of the blackness. A large, grey cloudbank was gliding lazily over the luminous full moon, shielding it from view.

Sirius smirked as he watched the shadowy form of Severus Snape shuffling down the path from the castle.

"Come on, Padfoot! We haven't got much time left." Remus called over his shoulder as he slipped between two roots of the currently motionless Whomping Willow. Peter followed him, eyeing the tree warily. Chuckling to himself, Sirius wove through the branches, smacking a few on his way, just for fun.

James, who was leaning against the trunk, turned. "What're you so cheerful about?"

Sirius grinned wickedly. "We're in for a bit of fun tonight," he said, pointing to the cloaked figure high above them on the path. "I've got some entertainment lined up."

James raised an eyebrow. They shared a nearly identical sense of humor, which they never failed to use at every opportunity. Sirius clapped him on the shoulder and jumped through the entrance into the hidden passage beneath. James followed, wondering what Sirius was planning. _So we'll give Snape a bit of a fright when he gets close enough. _He grinned at the thought. Sirius never missed a chance to bully Snape. Then something else came to mind. _What if he sees Remus?_ But he waved that thought away. Snape would never be able to get past the Whomping Willow.

Severus Snape, hooded and cloaked (students weren't allowed on the grounds after dark) stopped when he saw the Whomping Willow. It was perfectly still, as if carved from stone. As far as Snape knew, it was always moving, thrashing wildly if anything moved too close. So at least this was true – the tree could be controlled. But as he watched, the branches started waving sluggishly back and forth, like they were shaking off the remnants of sleep. As he neared, they picked up speed, flinging themselves toward him with terrifying force. One solid hit from one of the thicker branches would break any of his limbs. He swallowed slowly, remembering what Black had told him.

Normally, he tried not to pay attention to anything Sirius Black said to him, as it was always either an insult or a goad. But earlier today, Black had stayed behind after a routine round of abuse from his gang, and said in an off-hand sort of way, "I know you're trying to figure out what we've been up to. You're not being very subtle about it." Snape glared. "Well, here's your chance. Go to the Whomping Willow tonight after dark. There's a passage hidden between a couple of roots." Smirking, he turned to go.  
Snape grabbed his arm, holding him back. "I'm not an idiot." He hissed. "No one can get close to it. People have been trying all year and have ended up in the hospital wing. Not the smartest prank you've ever thought of, Black."

Twisting out of Snape's hold, he smiled. "There's a way. We've been managing it for quite a while. Just get a long stick and prod the little nob near the base of the trunk. The tree will freeze for about a minute." He ran off after Potter, Lupin, and Pettigrew, calling down the hall, "See you later, Snivellus!"

Now, as he watched the surging branches of the Whomping Willow, Snape wondered what the catch was. He knew there must be some sort of trick, something to make him look the fool, otherwise Black wouldn't have bothered speaking to him at all. _It wouldn't be worth his time_, Snape thought with a sneer. But the possibility of catching Potter and his gang in the act of something he was sure was at least suspension-worthy was too enticing. Since the start of the year, he'd noticed that they seemed to disappear every month, and he wanted very much to know where it was they disappeared to, and what they were doing. It seemed that no matter what Black and Potter did, they got away with barely a slap on the wrist. Snape had been waiting for some proper punishment for the things they did – not the least of which was their constant harassment of him – but most teachers were so enamored by their skills in the classroom, it didn't much matter that they got into trouble every now and again.

Looking around, he found a few twigs scattered on the path. He took out his wand, pointed at the thickest of the twigs, and muttered, "_Engorgio_." More confident now he had seen the tree in its frozen state, he picked up the now seven foot long pole and walked as near to the Whomping Willow as he dared. It strained toward him, limbs thrashing. Very carefully, Snape lay on his stomach and pushed the pole forward. He saw the nob on the truck, lifted the pole slightly and touched it. The tree froze instantly.

He raised his head. The branches were caught in mid swipe, the tree itself tilting forward. Quickly he scrambled up and wound his way toward the trunk. His minute was waning fast. Looking frantically for the passage Black had told him about, he kept one eye on the trunk, alert to any sign of movement. After several seconds of searching, he thought, _Maybe there is no passage._ Maybe this was the joke. Get him as close to the Whomping Willow as possible and watch it beat him to within an inch of his life. _They're probably standing a safe distance away, waiting for the show to begin_.

Just as he was considering turning back while he still had time, his foot caught on something and he pitched forward. But instead of falling flat on his stomach, he slid headfirst through a hole between two roots. He landed in a heap, face and arms covered with dirt. Breathing heavily, he turned over and sat up. As he blinked dust from his eyes, he heard an inarticulate sound from behind him. Turning, he saw James Potter looking dumbstruck at him. The astonished look on his face was almost enough to convince Snape that this little escapade had been worth the risk. He sneered, brushing strands of hair out of his face and standing. "What's the matter, Potter? Thought I wouldn't find out what you were up to?"

"What - how did you get down here?" He was fighting to wipe the surprise from his face.  
"Black told me. Where is he? I'll have to thank him. This is the last time you'll use this place as your little hideout, Potter. I wonder what the headmaster will say."

James Potter was frantically organizing his thoughts. This wasn't a complete disaster – if he could just get Snape to leave sooner rather than later. Quickly, he changed his expression to one of disdain. "What do you think will happen?" He said, looking pityingly down at Snape, whose pasty skin was smeared with dirt. "The worst you've found us doing is being out of bed after hours. That's only worth detention."

Snape's self-satisfied smirk flickered momentarily, then solidified. "This tree is out-of-bounds for students. That's worth more than detention."  
James snorted. "Yeah, but are you really so desperate that you'd risk the same punishment just to make sure we got our just desserts? That's pretty pathetic, even for you. Why don't you just go on back to bed, eh, Snivellus?"  
Snape flushed. "Shut up, Potter. What are you doing here anyway?"  
"Like we'd tell you," said a voice from the shadows. Sirius came up from behind James and threw an arm across his shoulders. He eyed Snape's disheveled clothes and dirty face. "So you decided to drop in then? Good." He grinned, then leaned toward James. "It's about time." Sirius whispered softly in his ear. "We should get going."  
"What are you two whispering about?" Snape shouted, annoyed.  
Sirius looked back at him indifferently. "You can come too if you like." He grinned again and started off down the passage.

James' eyes widened and he grabbed Sirius' arm. "You can't be serious," he hissed. "You're going to let him see?"  
"Of course not. Just scare him a little." The glint in Sirius' eyes worried James.  
"Come off it," James said, with forced nonchalance. "He's not worth it. And besides, we don't know if we can keep, uh, Mooney under control if there's a human running around down here."  
Sirius shrugged. "It's his own fault he showed up."  
"Because you told him too."  
"I just told him how get here."  
"You as good as dared him to come and catch us." James said, exasperated.

Snape, who had been listening with rapt attention, had no idea what they were talking about but he had a good idea it would get them into plenty of trouble. While they bickered, he began to inch his way back toward the opening he'd come through.

"Sirius, I think this crosses the line, even for you." James was feeling very nervous. This couldn't happen. The worst-case scenario was that Snape would see everything and tell everyone. Or he would be bitten. Either way, Remus would be forced to leave Hogwarts and who knows what would happen to the rest of them.

"_Locomotor mortis_," growled Sirius, suddenly. He'd raised his wand and was pointing it at Snape, who had been starting to climb out of the passage. His legs snapped together, and he fell back. "Now don't go running off, Snivelly." James grabbed Sirius' arm, but he pulled it free. "Don't be so worried, Prongs." Sirius said with a jaunty smile. "Everything'll be fine. And after this, he'll be too afraid of us to cause any more trouble." And with that he ran off down the passage.

James turned to Snape, who was wriggling on the floor, trying to reach his wand and snarling curses under his breath. James quickly performed the counter-curse and pulled him to his feet. Snape wrenched himself away and picked up his wand, aiming it at James.  
"What's going on here?" He demanded.  
James put up his hands. "Listen, you should leave. It's not safe for you here."  
"What do you mean it isn't safe? And why do you care anyway?" Snape was starting to get excited. This could be bigger than he thought – and the bigger the trouble, the worse the punishment.

"Snape, listen to me, just –

But at that moment, a gut-wrenching scream came from somewhere far down the passage, followed by pitiful sounding moans. James whipped around, staring wide-eyed into the dark.

Snape swung his wand in the direction of the sounds. "Wh-what was that?"  
James turned back toward him, looking panicked. "Snape, you have to go. Now!"  
"No!" Shouted Snape, sounding braver than he felt. "I want to know what's going on!"  
Another scream rent the air. This one sounded feral, more like a howl.  
James lunged forward, dragging Snape toward the hole between the roots. "Hurry! You've got to go!"

Snape fought him, twisting madly. He needed to know what they were doing, now more than ever. "What's happening? What are those noises?"  
James gasped with the effort of holding onto him. "No time…to explain." He huffed. He turned and pushed Snape as close to the hole as he could. "Just go!" He yelled.

Snape was about to try and punch him when a furious barking came from behind them. He turned to see an enormous black dog hurtling down the tunnel. It stopped several feet away, growling at them menacingly. Then it turned and stared back the way it had come, hunched and waiting.

"Come on!" Snarled James, who had hoisted himself up through the entrance to the tunnel. He held a hand out to Snape, but Snape ignored it. He could feel the tension building. He was sure he was about to learn everything. The dog started barking again, and Snape could hear something else charging down the tunnel. It sounded very big.  
"Snape, move it!" Yelled James grabbing the hood of his cloak. He was being dragged backward, the neck of the cloak tight around his throat, but still he stared down the tunnel, waiting to see what was coming.

James pulled until he could grab Snape's arm. He couldn't let him see Remus, not like this. And he couldn't let Remus hurt anybody. He'd never forgive himself. So he dragged the struggling Snape until he had a solid hold under both arms. He started to heave him up between the roots.

Snape could see a monstrous shape sprinting down the tunnel. As it came closer, he saw its yellow eyes and heard its jaws snapping violently. Snape felt his body go rigid with fear. This was far beyond anything he had expected. The thing, the monster, drew nearer with every bound, but all of a sudden, the dog lunged at it and they tumbled backward in a rolling mass of black fur and gnashing teeth. The monster howled its frustration, straining against the dog, it's crazed eyes fixed on Snape.

James felt Snape's body seize up and hauled him out of the tunnel, onto the ground at the base of the Whomping Willow. Snape looked around wildly, in shock, then fixed his black eyes on James. He stood shakily and opened his mouth, but was thrown forward by a swinging branch. James ducked another, grabbed a fistful of Snape's clothing and starting running. He could feel Snape stumble behind him, when another branch caught him in the stomach. He flew backward. Barely breathing, he staggered to his feet, got hold of Snape again and they pelted beyond the reach of the Whomping Willow. When they reached a safe distance, James released his hold and Snape scrambled away from him. Eyes wide and confused, he stared at James, who was clutching his stomach, trying to remember how to breathe.

James didn't know how much Snape had seen, but he could guess. Because when he looked up and started to say, carefully, "Severus…" Snape had clambered to his feet and begun to stumble up the path toward the castle without looking back. James knew he was on his way to Professor Dumbledore. But that wasn't what he was worried about. Obviously, Dumbledore knew all about Remus' problem. No, James was worried that if Snape came across anyone else before he got to the headmaster's office he would tell them, and then everything would be ruined.

Knowing there was nothing he could do, he stood and went to help Sirius.

* * *

**NOTE:** So I recently reread The Prisoner of Azkaban and learned why Snape hates James so much: because James saved his life. I was so intrigued by how this would change all the characters involved that I decided to write it :) This is the first part in a two-shot. The second part will be shorter (I think) and focus on the repercussions of all this, including a bit about Lily and James.

Review please :D I always enjoy feedback!

-Mel


	2. Part II

_**Crossing the Line: Part II**_

As soon as Remus had transformed back into an exhausted human being, James, Sirius and Peter had helped him up to the castle. Instead of heading to their dormitory, as they normally did, they went straight to the headmaster's office, knowing there was no other way to deal with the situation. As they stood before the gargoyle that guarded the entrance, they realized none of them knew the password.

"I wonder if it's the same as the last time I was here. It wasn't that long ago." James mused. He cleared his throat. "Pepper Imp." He said loudly. The gargoyle didn't move. He sighed. "Ah well, it was worth a try, I suppose."

Remus lifted his head from James' shoulder and gasped, "Candyfloss." The Gargoyle leapt aside, allowing access the rotating spiral staircase that led to Dumbledore's office. All three of his companions looked at him, impressed. He let his head fall back onto James' shoulder. "I came by a couple of days ago. He likes to keep me updated on the latest discoveries about werewolves." He heaved a sigh and straightened. He looked dreadful. This had been a particularly bad transformation, and when James had told him what had happened with Snape, he had taken it very badly. All energy seemed to have left him, and he wouldn't even look at Sirius.

James kept his arm around Remus' shoulders and they stepped onto the staircase. Immediately it began to move. Peter, looking terrified, hopped awkwardly after them. Sirius waited a few moments so there would be a few steps between them, then climbed onto the stair. When they reached the door, James lifted a hand and knocked slowly, three times. It sounded like the pounding of a judge's gavel, deciding their fate.

After a few moments, the great oak doors opened and Professor Dumbledore stood before them. He looked down over his half-moon spectacles, eyes unreadable. "I am certainly glad to see that you four are alright." He said evenly, looking at each of them in turn. "Though I must express my astonishment that we have found ourselves in the current situation." His eyes drifted to Sirius, who lowered his head. "However, I am currently discussing matters with Mr. Snape."

"Professor – " began James, but Dumbledore raised a hand for silence.

"I am attempting to explain this, ah, misadventure to him. I will need some time." He glanced at Remus' white face and sunken eyes. "Perhaps, in the interim, Mr. Pettigrew might escort Mr. Lupin to the hospital wing?" He eyed Peter significantly, who jumped to follow his suggestion. James transferred Remus to Peter, whose small body sagged under the weight. "You two," he looked from James to Sirius, "may wait here until I have finished with Mr. Snape." He turned and the doors closed with an ominous thud behind him.

For a moment, nobody moved. James gave Peter a shove. "Well, off you get. Remus needs some rest." Peter and Remus cautiously made their way down the staircase and into the corridor. As they disappeared from view, James turned to Sirius. "What the bloody hell were you thinking, Sirius?" He said flatly. Sirius didn't move. He was leaning against the wall, eyes downcast. "Tell me."

Slowly, Sirius lifted his head. He looked very tired. He met James' eyes for a second then looked away, mumbling something.  
"What?" James asked, feeling the anger writhe in his chest.  
"I don't know."  
"You don't know." Repeated James. Sirius glanced at him, and looked away again.  
"Yeah."  
James snorted derisively.  
Sirius looked straight at him this time. "Honestly, I don't know what I was thinking!" He said, louder. "I thought it'd be a laugh to really give him a scare, not just tease him. He's such an easy target but he makes enough trouble for us, doesn't he? Always trying to figure out what rules we're breaking and stuff."

James felt hot, scalding disappointment in his friend. "So you thought it'd be funny to see what would happen if you put him up against a _werewolf_?" He hissed. "You realize he could've been killed? Or bitten? Do you think Remus would ever forgive himself if he bit someone?"  
Sirius looked at him, a pleading look in his eyes. "I only meant for him to hear the noises. They're scary enough on their own. Then he was supposed to run away."  
"Well obviously you underestimated him."  
"Yeah, who'd have guessed Snivellus was that brave?" He attempted a smile, but it withered under James' icy glare. He sighed. "I thought if we all stuck around Remus after he transformed, we could keep him in check while Snape ran, but then you stayed with him and tried to help him –  
"So it's my fault?" James yelled.  
"No!" Sirius shouted back. "But, you stayed with Snape, so I ran to help Peter but Remus was already transforming, and there's only so much Peter can do, you know? Before I knew it, the transformation was over, and it had been a really bad one, you could tell. I was the only one of us left around. So I booked it back down the tunnel to warn you and tried to hold him off while you got Snape. You know the rest."

James did. When he'd returned to the tunnel to help Sirius, he and Remus had been locked in a ferocious battle of teeth and claws. James had transformed and together, he and Sirius had forced Remus back into the room at the end of the tunnel where they kept him until he became human again.

Sirius sank to the stone floor. James, still angry, sat beside him with a sigh. "I guess something like this was bound to happen sooner or later." Sirius looked up. "I mean, we've been going at him for years, haven't we? One of us was eventually going to raise the stakes. You were just the first one to think of it." He ran a hand through his hair, making some stick up at the back.

Sirius let his head fall back against the wall. "At least nothing happened."  
James glared at him, "Nothing happened?"  
Sirius looked defiant. "Well no one actually got hurt, did they?"  
"That's not that point!"

At that moment, the oak doors opened and Dumbledore appeared, followed by a furious looking Snape. James and Sirius scrambled up. Dumbledore laid a hand on Snape's shoulder. "You may go. But remember what I have told you." Snape shrugged Dumbledore's hand off and started down the stairs. As he passed James, he gave him such a look of pure loathing that James took a step back in surprise.

Cautiously, Sirius and James followed Dumbledore into his office. It was familiar to them; they had been here many times before. Faux the phoenix was drowsing on his perch. All the silvery instruments shone in a peaceful sort of way. However, almost every single portrait of a Hogwarts Headmaster or Headmistress was glowering down at them. A few were still asleep.

"Sit, please," said Dumbledore. They sat. "I think I need not explain to you the severity of the situation." He looked at them over his half-moon spectacles. "I'm sure you are well aware of how your little prank could have had very deadly consequences." He paused. "Am I wrong?"  
"No, sir." They both said.  
"That's good." He smiled briefly. "I thought if I let you to discuss it for a while on your own, you might come to the same conclusion I have. Especially considering Mr. Potter's expression when you first arrived."

James and Sirius looked at him warily.

"I am well aware that you have been personally victimizing Mr. Snape for some time now. I had hoped the thrill of it would dissipate as time went on, but I was proven wrong. Which does not happen very often, I might add." Another pause. "However, I believe this incident may have provided you both with some much needed perspective."

He eyed them both, waiting for a response. They nodded. "Good. Punishment is warranted, I fear." Sirius bowed his head again. James stared at a point beyond Dumbledore's head, waiting for the axe to fall. "I think, one hundred points will be taken from Gryffindor for Mr. Black's alarming lack of judgment. Your Hogsmeade visitation privileges are suspended until further notice, and you will serve detention with Professor McGonagall every Saturday evening until the end of term. Mr. Potter –" James jumped. "You will serve detention with Mr. Black for half of his given time. But," he raised his voice over Sirius' objections that he was the only one to blame. "You will receive fifty points for Gryffindor for protecting the life of an enemy in spite of your friend and in the face of great personal risk." Both James and Sirius were stunned. Dumbledore continued. "Despite your admittedly reprehensible behavior toward Mr. Snape in the past, you set aside your personal antagonism to save his life, regardless of the danger to yourself. You acted admirably, and made Gryffindor House very proud." He smiled at both of them. "You may go."

James and Sirius stood, bewildered, and turned to leave. As they walked toward the doors, James suddenly remembered something. "Sir?"  
"Yes?"  
"What about Snape?"  
"What about him?" Dumbledore's mouth twitched.  
"Well, how did you explain everything?"  
"I told him the truth."  
Sirius gasped. "But—  
"I told him that your friend is a werewolf and that I planted the Whomping Willow to provide him and others with protection during his transformations. I also told him that should he tell anyone those details, he would be expelled." He gazed at them carefully. "I hope this satisfies your curiosity." They nodded slowly. "Then you may leave."

Naturally, by midday everybody was talking about how James Potter saved Severus Snape from the Whomping Willow. Though the rumors themselves were mostly false, the essential detail – that James had saved Snape – remained intact. James supposed Snape must have complained to one of his cronies and been overheard. By dinner, people were coming up to him, asking him things like, "Is it true five branches were pinning him down?"  
"I heard half his ribs got broken and you pulled him out without a scratch!" At this, James lifted his shirt and showed off the gloriously black and purple bruise that was blossoming over his midsection. Girls squealed and boys shuddered in sympathy. Snape was nowhere to be seen.

Sirius was receiving similar treatment. While everyone knew James had pulled Snape out of clutches of the murderous tree, they also knew that Sirius was the one who had convinced him to go to the Whomping Willow in the first place. He wasn't taking the attention very well. The last boy to clap him on the shoulder and say, "Well played, Sirius," was rushed to the hospital wing with a broken nose. When a girl walked by them in the corridor and laughed, "Wish I'd seen his face!" Sirius punched the wall so hard, his knuckles started to bleed.

James was trying to get Sirius to let him use a healing charm when they rounded a corner and ran headlong into someone carrying two large boxes. The boxes went flying, their contents going everywhere. James, Sirius, and the person they had hit were lying in a heap on the floor. James had fallen on top of somebody but he'd lost his glasses in the melee and couldn't tell who it was. A grunt from his left told him it wasn't Sirius. Then, a familiar voice growled, "Get off me, Potter!" and he was shoved backward so hard he slid a few inches on the stone floor. He found his glasses and put them on, blinking rapidly. It was Lily Evans.

She stood and smoothed her robes. Her red hair was tangled and her robes dusty, but James thought she had never looked more pretty. Her eyes flickered angrily as she surveyed the damage of their latest run-in. Sirius sat up, rubbing his head. "Hi, Lily." He said, grumpily.

"Hello, Sirius." She muttered, taking out her wand. Instinctively, James reached for his own and quickly scrambled to his feet. Lily blinked, looking bemused, then laughed. She had a lovely laugh, strong and carefree. Grinning mischievously at James, she said, "Don't worry, Potter. I'm not going to hex the man of the hour." She flicked her wand in a series of complex combinations and the contents of her boxes began to reorganize themselves.

James rubbed the back of his neck in embarrassment. Snape was one of Lily closest friend's. Or had been. A while ago, James had been using him as a test subject for the popular spell _levicorpus_. Lily had come to his defense but in thanks he'd called her a mudblood. It was one of the reasons James' hatred of him had intensified over the last few months. He didn't know if Lily had forgiven him or not, so he decided to tread carefully, lest he antagonize her. He really wasn't in the mood to be hexed.

He watched admiringly as all the bits of paper, crushed inkbottles, and other things repaired and rearranged themselves neatly into their boxes. Lily really was superb at charms.

Lily surveyed her handiwork. It was as if nothing had happened. Professor Flitwick would be pleased. Suddenly she remembered she wasn't alone. She glanced up to see James Potter staring at her with a very odd expression on his face: a shy smile. "What are you thinking?" she asked before she could stop herself.

He looked surprised, and rightly so, she'd never asked him something like that before. "Uh," he blushed a little, "I was thinking that you're really good at charms."

"Oh." She felt her cheeks warm. He roughly ran a hand through his black hair, making it even untidier. She found he did this either when he was nervous or when he was flirting. She couldn't really tell which it was at the moment.

"What about you?" He asked.  
She looked blankly at him. "What?"  
"What are you thinking about?"

She felt her whole face flush. She stooped to pick up her boxes, letting her long red hair shield her blushing. Rather than say she was wondering if he was flirting with her, she said, "I was wondering if it was true. You know, about Severus." She frowned as she said his name. It still hurt to remember the way he'd called her 'mudblood' so easily.

"Uh, yeah, sort of."  
She looked up at him, raising an eyebrow. "Sort of?"  
He shrugged. "Well, half his ribs aren't broken and he wasn't pinned down or anything. I just grabbed him and pulled him out before he got really hurt, that's all."  
"Oh my, is James Potter being modest?" She was finding her footing again. Sarcasm was safer ground.

He grinned. "Well I'm not denying I saved his life, am I? I mean, that's the most important part." As she stood, he took the boxes from her arms. From behind them he asked, "Now, where do these go?"

Sirius smiled as he watched Lily and James walk toward the charms corridor together, laughing and talking the way friends should, completely forgetting his existence. _And they're already friends_, Sirius thought as he made his way to the hospital wing, _even if they haven't realized it yet_.

* * *

**NOTE:** So this turned out way longer than I planned it to be. I hope it wasn't too boring :/ I just wanted to look at the repercussions of James saving Snape. I think the main changes were James matured a bit and stopped bullying Snape as much. I didn't touch on that a lot, but I do hope I made it obvious enough that Sirius felt guilty. What I did want to touch on was the beginning of Lily's crush on James. I think this is really the turning point in their relationship: James matures and Lily sees the good in him and falls for him.

Thanks for reading! Review please :)

-Mel


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